The Ecology of Tijuana Estuary, California: An Estuarine Profile

PREFACE
Throughout the history of wetland studies, people have argued about the similarity
of wetlands - with views ranging froin "all wetlands are alike" to "every wetland is
unique." The truth lies somewhere in between, such that wetlands share many
features (e.g., the importance of hydrology in controlling habitat type) but also have
unique qualities. In this Estuarine Profile, we try to point out how the various
properties of Tijuana Estuary compare to those of other estuaries within the region as
well as within the nation. The designation of Tijuana Estuary as one of the National
Oceanic and Atmospheric Administration's National Estuarine Sanctuaries shows that
it is one of a class of ecosystems worthy of research and education, yet different
enough to warrant selection as a regional type.
What makes Tijuana Estuary eligible for national recognition? It functions as a
coastal water body that is influenced by both marine and river waters. It supports a
range of natural plant and animal communities that are especially adapted to
withstand the variable salinities that occur when sea and fresh waters mix. It has
persisted through human history as a natural ecosystem that retains many of its
natural qualities despite disturbance from urban and agricultural land uses. Unique to
Tijuana Estuary is its international setting, with three-fourths of its watershed in
Mexico; its diversity of ecological communities, which provide habitat for a variety of
rare and endangered species; and its history of ecological study, with extensive data
from years with and without catastrophic disturbances.
What sets Californ~a's estuaries apart from others In the nation is the degree of
variability rn the physical env~ronrnent Dur~ng most of the year, they are marrnedom~nated
systems, i e, extensions of the ocean During the winter rainy season, they
may become completely fresh In addition, there IS substantial annual variation from
years with no streamflow to years w~th major floods The extremely var~able nature of
southern California's coastal habitats IS not evldent from short-term observation
indeed, many v~sitors enjoy weeks of warm, cloud-free days and deny that we even
have "weather" But from over a decade of study, there have been repeated
opportunities to w~tness extreme events within Tijuana Estuary, ranging from
catastroph~c floodtng to unprecedented drought These events have in turn allowed us
to identify how physical factors influence b~otic communities, and to quantlfy the
dynamics of estuarine organisms as they respond to environmental extremes
Comments concerning or requests for this publication should be addressed to.
Information Transfer Spec~allst
National Coastal Ecosystems Team
U S Flsh and Wildlife Service
NASA-Sl~dell Computer Complex
1010 Gause Boulevard
Slidell, LA 70458
(504) 646-7287, Ff S 680-7287
iii